World of Water Study Guide THE LAST ONE - World of Water...

World of Water Study Guide: Exam IV 02/12/2007 22:00:00 ← 1. Know the percentage of earth’s water in groundwater and soil water • Groundwater: 0.6% • Soil: 0.001% ← 2. The radius of the earth is approximately 4000 miles, the average depth of oceans is 2.3 mile, soil = meters. • Soils: 0.001 miles ← 3. Know the major components of soils (e.g. mineral particles) and their % in an idealized surface soil. • Gas: 25% • Liquid: 25% • Solid: 50% (45% inorganic, 5% organic) ← 4. Know essentially how particle size (large vs. small) impacts soil porosity. • Soil pores form a network of spaces within the soil which conduct and retain water and gases. Pores may be completely or partially filled with water. • Water flows and is retained in soil pore spaces. Impacts on pore spaces impact water flow. ← 5. Know the value for soil particle density and the appropriate units. • Particle density: 2.65 g/cm^3 ← 6. Be able to calculate the bulk density of a soil and know the difference between particle and bulk density. • Bulk Density= mass Oven Dried Soil/ volume solids + pores • Bulk Density: density of soil including the particles and the pore spaces • IT MEASURES THE MASS OF THE OSIL SOLIDS IN RELATION TO THE VOLUME OF THE SOIL SOLIDS AND THE SOIL PORES • Particle Density: density of individual soil particles • Particle density= mass of particle/ volume of particle

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← 7. Know the relationship between bulk density and porosity. Be able to calculate porosity from bulk density. • Since the density of the particles is a constant, the only thing that can impact bulk density is the porosity. The greater the porosity, the lower the bulk density. • Porosity= Volume of pores/Volume of soil • Total porosity-> total water capacity • % Porosity= [1-(BD/PD0] X 100 • P= 20- 60% ← 8. Know the three soil separates and be able to rank them according to size. • Sand: 2.0- 0.05 mm • Silt: 0.0f- 0.002 mm • Clay: <0.002 mm ← 9. Know the two forces that move water in soils. • Gravity and Capillarity

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